1. Field of the Invention
The present invention relates to a method for manufacturing a coated sheet. A method of this invention is useful in formation of, for example, an optical functional layer. In particular, this invention relates to an optical element using the optical functional layer concerned. The optical elements etc. are suitably utilized in various image display devices, such as liquid crystal displays (LCD), organic electrolumine scence display devices, PDPs, and CRTs.
2. Prior Art
Conventionally, various kinds of coated sheets obtained by forming a coated layer by way of giving processes, such as coating, drying, etc. of a coating liquid onto a surface of a base material film have been manufactured. As coating method for the above-mentioned coating liquid, various methods, such as a slot die method, a reverse photogravure coating method, and a micro photogravure method, are adopted.
As coated sheets, for example, various kinds of optical films having optical functional layers may be mentioned. The optical functional layers are formed with thin films in connection with performance upgrading in optical function. When a film thickness of the thin film concerned has irregularity, display capabilities in an image display devices using this film, such as liquid crystal display, will be deteriorated. Accordingly, it is required that the optical functional layer should have a uniform film thickness. It was, however, difficult to form a coated layer with a uniform film thickness. Particularly it was difficult to form a coated layer with a uniform film thickness onto a base material film having a large area.